1. Field of the Instant Disclosure
The instant disclosure relates to a method of forming a multicolor surface; in particular, to a method of forming various colors and surface effects on a substrate through multiple anodic treatments.
2. Description of Related Art
Mobile electronic devices, such as cell phones, personal digital assistants (PDAs), and computers, are being widely used today. Generally, consumers are more attracted by products which are aesthetically appealing. Therefore, housings of various electronic devices usually have shiny and smooth metallic surfaces manufactured by various processing means.
In particular, anodic oxidation is being utilized for dyeing the metallic housings. Nevertheless, by using such means, only one single color can be formed on the housing surface without other color variations.
To form oxide layers having different colors on a metallic housing, the housing may undergo multiple anodizations and dyeing processes. Specifically, a masking ink is used to cover areas of the metallic housing not to be surface treated. After the anodization has been completed, the masking ink is then removed. Such process is more complicated and requires additional expenses for the masking procedure, thus incurring a higher manufacturing cost.
Another existing method of forming a two-color housing is to partially remove a first oxide layer from the outer surface of the housing after the first anodization. Then, a second oxide layer that can be dyed with a second color is formed by a second anodization. In order to overcome the conducting problem for the second anodic oxidation, one solution is to remove the first oxide layer from the inner surface of the housing by means of grinding to provide a conductive area for the electrodes. However, such method has limitations in that the removed thickness of the first oxide layer is uneasy to control, where too much grinding may damage the housing. Whereas if the first oxide layer is not totally removed from the inner surface of the housing, the conductivity may suffer and negatively impact the second anodic treatment. Furthermore, if a third color is preferred to be formed on the housing, the same grinding process must be repeated, which further increases the risk of damaging the housing.
Therefore, it is an urge for the industry to find a method of producing multiple colors on the housing surface.
To address the above issues, the inventors strive via industrial experience and academic research to present the instant disclosure, which can effectively improve the limitations described above.